The invention relates to a network interface of a computer network having at least two bus lines and a plurality of substations interconnected by the bus lines. In particular, the present invention relates to a method of and a device for activating such a network interface out of a sleep mode into a wake-up mode even in the case of a failure of one bus line.
Computer controlled networks are being used more and more frequently, in particular also in motor vehicle construction. In particular, so-called controller area network interfaces for motor vehicles are known, which connect via the bus lines a multiplicity of components, subsystems and/or systems forming the respective substations of the network. The information items or bits of the network run via the two bus or signal lines. Any failure of one of the two signal lines due to short-circuiting to ground or to the voltage supply or an interruption of the lines has the consequence that communication among substations of the entire network breaks down. This is also the case if a short-circuit occurs between the two bus lines.
In my German Patent Application P 38 26 774, corresponding to U.S. patent application Ser. No. 466,283, filed Mar. 19, 1990 and assigned to the same assignee, it has been proposed for the detection and elimination of a global fault on the signal lines of the multiplex bus to provide the network interface with a fault detection device including a counter, with the aid of which an absence of information on the signal lines can be detected. However, the detection is possible only in the wake-up mode of operation of the interface.